Bacteroides ovatus alleviates dysbiotic microbiota-induced graft-versus-host disease.

Acute lower gastrointestinal GVHD (aLGI-GVHD) is a serious complication of allogeneic hematopoietic stem cell transplantation. Although the intestinal microbiota is associated with the incidence of aLGI-GVHD, how the intestinal microbiota impacts treatment responses in aLGI-GVHD has not been thoroughly studied. In a cohort of patients with aLGI-GVHD (n = 37), we found that non-response to standard therapy with corticosteroids was associated with prior treatment with carbapenem antibiotics and a disrupted fecal microbiome characterized by reduced abundances of Bacteroides ovatus. In a murine GVHD model aggravated by carbapenem antibiotics, introducing B. ovatus reduced GVHD severity and improved survival. These beneficial effects of Bacteroides ovatus were linked to its ability to metabolize dietary polysaccharides into monosaccharides, which suppressed the mucus-degrading capabilities of colonic mucus degraders such as Bacteroides thetaiotaomicron and Akkermansia muciniphila, thus reducing GVHD-related mortality. Collectively, these findings reveal the importance of microbiota in aLGI-GVHD and therapeutic potential of B. ovatus.

Tsyn-Seq: a T-cell Synapse-Based Antigen Identification Platform.

Tools for genome-wide rapid identification of peptide-major histocompatibility complex targets of T-cell receptors (TCR) are not yet universally available. We present a new antigen screening method, the T-synapse (Tsyn) reporter system, which includes antigen-presenting cells (APC) with a Fas-inducible NF-κB reporter and T cells with a nuclear factor of activated T cells (NFAT) reporter. To functionally screen for target antigens from a cDNA library, productively interacting T cell-APC aggregates were detected by dual-reporter activity and enriched by flow sorting followed by antigen identification quantified by deep sequencing (Tsyn-seq). When applied to a previously characterized TCR specific for the E7 antigen derived from human papillomavirus type 16 (HPV16), Tsyn-seq successfully enriched the correct cognate antigen from a cDNA library derived from an HPV16-positive cervical cancer cell line. Tsyn-seq provides a method for rapidly identifying antigens recognized by TCRs of interest from a tumor cDNA library. See related Spotlight by Makani and Joglekar, p. 515.

Microbiome alteration via fecal microbiota transplantation is effective for refractory immune checkpoint inhibitor-induced colitis.

Immune checkpoint inhibitors (ICIs) target advanced malignancies with high efficacy but also predispose patients to immune-related adverse events like immune-mediated colitis (IMC). Given the association between gut bacteria with response to ICI therapy and subsequent IMC, fecal microbiota transplantation (FMT) represents a feasible way to manipulate microbial composition in patients, with a potential benefit for IMC. Here, we present a large case series of 12 patients with refractory IMC who underwent FMT from healthy donors as salvage therapy. All 12 patients had grade 3 or 4 ICI-related diarrhea or colitis that failed to respond to standard first-line (corticosteroids) and second-line immunosuppression (infliximab or vedolizumab). Ten patients (83%) achieved symptom improvement after FMT, and three patients (25%) required repeat FMT, two of whom had no subsequent response. At the end of the study, 92% achieved IMC clinical remission. 16S rRNA sequencing of patient stool samples revealed that compositional differences between FMT donors and patients with IMC before FMT were associated with a complete response after FMT. Comparison of pre- and post-FMT stool samples in patients with complete responses showed significant increases in alpha diversity and increases in the abundances of Collinsella and Bifidobacterium, which were depleted in FMT responders before FMT. Histologically evaluable complete response patients also had decreases in select immune cells , including CD8+ T cells, in the colon after FMT when compared with non-complete response patients (n = 4). This study validates FMT as an effective treatment strategy for IMC and gives insights into the microbial signatures that may play a critical role in FMT response.

Mucocutaneous adverse events to immune checkpoint inhibitors.

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy. Since the approval of ipilimumab in 2011, a total of nine ICIs have gained indications for various solid and hematologic malignancies. The expanding use of ICIs in oncology underscores the need for diagnosis and treatment expertise in immune related adverse events (irAE). Cutaneous toxicities are the earliest and most common irAE in this class of therapy. In addition to the more frequent reactions including vitiligo, lichenoid dermatitis, psoriasiform dermatitis, other less common skin toxicities including bullous dermatoses, neutrophilic dermatoses, and autoimmune dermato-rheumatologic diseases have been reported. Even though less than 3% of cutaneous irAEs (irCAEs) are classified as grade 3 or higher events, irCAEs can greatly impact quality of life. Appropriate management of irCAEs is critical to avoid unwarranted interruptions or discontinuation of lifesaving immunotherapy.

Bacteroides ovatus alleviates dysbiotic microbiota-induced intestinal graft-versus-host disease.

Acute gastrointestinal intestinal GVHD (aGI-GVHD) is a serious complication of allogeneic hematopoietic stem cell transplantation, and the intestinal microbiota is known to impact on its severity. However, an association between treatment response of aGI-GVHD and the intestinal microbiota has not been well-studied. In a cohort of patients with aGI-GVHD (n=37), we found that non-response to standard therapy with corticosteroids was associated with prior treatment with carbapenem antibiotics and loss of Bacteroides ovatus from the microbiome. In a mouse model of carbapenem-aggravated GVHD, introducing Bacteroides ovatus reduced severity of GVHD and improved survival. Bacteroides ovatus reduced degradation of colonic mucus by another intestinal commensal, Bacteroides thetaiotaomicron, via its ability to metabolize dietary polysaccharides into monosaccharides, which then inhibit mucus degradation by Bacteroides thetaiotaomicron and reduce GVHD-related mortality.

Systemic Treatment of Cutaneous Adverse Events After Immune Checkpoint Inhibitor Therapy: A Review.

As treatment with immune checkpoint inhibitors (CPIs) for cancer increases, so has the incidence of immune-related cutaneous adverse events (irCAEs). These toxicities can significantly impact quality of life and may be dose-limiting. Current guidelines for irCAEs offer only corticosteroids or CPI discontinuation. Evidence supports biologic immunomodulatory therapies when corticosteroids fail or need avoidance. A review of literature from 2010 to 2020 yielded 45 articles, resulting in 185 irCAEs, including bullous pemphigoid-like eruption (n = 55), psoriasis/psoriasiform dermatitis (n = 41), and maculopapular rash (n = 31). Treatments included immunomodulators, intravenous immunoglobulin, aprepitant, acitretin, tetracyclines, and biologic agents. Overall, 92.3% of patients saw improvement or resolution of their rash. Bullous pemphigoid-like eruptions were treated with a tetracycline +/- niacinamide (94.7% success [18/19]), omalizumab (100% success [7/7]), and rituximab (100% success [10/10]). Although prospective research is required, this review provides a comprehensive list of successful, non-corticosteroid treatment options for irCAEs to improve compliance with lifesaving cancer therapy.

Diet-derived metabolites and mucus link the gut microbiome to fever after cytotoxic cancer treatment.

Not all patients with cancer and severe neutropenia develop fever, and the fecal microbiome may play a role. In a single-center study of patients undergoing hematopoietic cell transplant (n = 119), the fecal microbiome was characterized at onset of severe neutropenia. A total of 63 patients (53%) developed a subsequent fever, and their fecal microbiome displayed increased relative abundances of Akkermansia muciniphila, a species of mucin-degrading bacteria (P = 0.006, corrected for multiple comparisons). Two therapies that induce neutropenia, irradiation and melphalan, similarly expanded A. muciniphila and additionally thinned the colonic mucus layer in mice. Caloric restriction of unirradiated mice also expanded A. muciniphila and thinned the colonic mucus layer. Antibiotic treatment to eradicate A. muciniphila before caloric restriction preserved colonic mucus, whereas A. muciniphila reintroduction restored mucus thinning. Caloric restriction of unirradiated mice raised colonic luminal pH and reduced acetate, propionate, and butyrate. Culturing A. muciniphila in vitro with propionate reduced utilization of mucin as well as of fucose. Treating irradiated mice with an antibiotic targeting A. muciniphila or propionate preserved the mucus layer, suppressed translocation of flagellin, reduced inflammatory cytokines in the colon, and improved thermoregulation. These results suggest that diet, metabolites, and colonic mucus link the microbiome to neutropenic fever and may guide future microbiome-based preventive strategies.

Mucus-degrading Bacteroides link carbapenems to aggravated graft-versus-host disease.

The intestinal microbiota is an important modulator of graft-versus-host disease (GVHD), which often complicates allogeneic hematopoietic stem cell transplantation (allo-HSCT). Broad-spectrum antibiotics such as carbapenems increase the risk for intestinal GVHD, but mechanisms are not well understood. In this study, we found that treatment with meropenem, a commonly used carbapenem, aggravates colonic GVHD in mice via the expansion of Bacteroides thetaiotaomicron (BT). BT has a broad ability to degrade dietary polysaccharides and host mucin glycans. BT in meropenem-treated allogeneic mice demonstrated upregulated expression of enzymes involved in the degradation of mucin glycans. These mice also had thinning of the colonic mucus layer and decreased levels of xylose in colonic luminal contents. Interestingly, oral xylose supplementation significantly prevented thinning of the colonic mucus layer in meropenem-treated mice. Specific nutritional supplementation strategies, including xylose supplementation, may combat antibiotic-mediated microbiome injury to reduce the risk for intestinal GVHD in allo-HSCT patients.

A retrospective chart review of management strategies for lichenoid eruptions associated with immune-checkpoint inhibitor therapy from a single institution.

Immune checkpoint inhibitors and their associated immune-related cutaneous adverse events are continuing to become a mainstay of cancer treatment regimens. While most rashes are mild and easily manageable, severe or persistent rashes like lichenoid dermatoses can significantly impact the quality of life and may require ICI cessation. Lichenoid dermatoses currently have no management guidelines beyond the use of topical or oral steroids. Our study is a single-institution retrospective chart review to characterize ICI-induced lichenoid eruptions, their treatments, and associated tumor response. We utilized natural language processing and our institutional medical record to identify patients with lichenoid eruptions on ICI therapy. One-hundred nineteen patients were identified, of which 108 rashes were characterized as lichenoid dermatitis and fifteen as lichenoid mucositis. Most patients presented with a diffuse distribution (86%, 101/117), with pruritus in lichenoid dermatoses (82%, 89/108) and pain in lichenoid mucositis (80%, 12/15). Successful treatments for lichenoid dermatitis included topical steroids (81%, 88/108), oral antihistamines (21%, 23/108), and oral steroids (15%, 16/108). Of lichenoid dermatitis patients, 21% (23/108) did not respond to treatment (7) or required oral steroids (16). Approximately 28% of patients who had lichenoid dermatitis had delay, reduction, or discontinuation of their ICI because of their irCAE. This descriptive study highlights the impact of lichenoid dermatitis on patients' ability to remain on ICI therapy and the need for more effective non-steroidal management strategies.

Use of Indoor Tanning Diagnosis Codes in Claims Data.

The International Classification of Diseases: 10th Revision (effective from October 2015) included indoor tanning diagnosis codes for the first time. The majority of data on indoor tanning is self-reported. We used a large claims dataset to investigate the patients and settings in which indoor tanning International Classification of Diseases: 10th Revision codes are being used. We included encounters with the International Classification of Diseases: 10th Revision indoor tanning codes in Truven Health MarketScan data 2016-2018, which contain deidentified commercial insurance claims data for approximately 43 million patients. We used descriptive statistics to evaluate patient and encounter characteristics and normalized results using outpatient dermatology encounters. A total of 4,550 encounters were identified, 99.0% of which were outpatient, and 72.3% were with dermatology. Patients were majority female (85.0%) with ages ranging from 7 to 93. The Midwest region had the most indoor tanning encounters. Destruction of a premalignant lesion was performed in 15.1%, and biopsies were performed in 18.4% of encounters, suggesting that encounters may have been for skin cancer surveillance. Increased usage of indoor tanning International Classification of Diseases: 10th Revision codes in the coming years may strengthen the indoor tanning literature. Claims data are a potential tool to better understand patients who have a history of exposure to indoor tanning and their associated risk factors, comorbidities, behaviors, and healthcare utilization.

Dietary carotenoids do not improve motility or antioxidant capacity in cichlid fish sperm.

Carotenoids may act as antioxidants under many circumstances. We examined the importance of carotenoids as antioxidants in the gonads of male convict cichlids (Amatitlania nigrofasciata), a species in which males lack the carotenoid-based breeding coloration that characterizes females. Male fish were fed one of four diets that included different combinations of xanthophyll and carotene carotenoids, and then we measured carotenoid concentration of the gonads, gonadosomatic index (GSI), sperm motility, and the antioxidant capacity of the gonads. Significant differences were found in gonadal carotenoid content among treatment groups, suggesting that dietary carotenoids were indeed sequestered in the gonads. There were no differences among diet groups, however, in GSI, sperm motility, or gonadal antioxidant capacity. These findings suggest that carotenoids are required only in small amounts in the testes of male convict cichlids or that they play a limited role in protecting sperm from oxidative damage.

Exposure to 17α-ethinylestradiol decreases motility and ATP in sperm of male fighting fish Betta splendens.

The synthetic estrogen 17α-ethinylestradiol (EE2) is an endocrine-disrupting chemical released into aquatic environments from sewage treatment facilities. We tested the effects of two environmentally relevant concentrations of waterborne EE2, 10 and 100 ng L(-1) , on reproductive endpoints in the teleost fish Betta splendens. In the first experiment, testes were removed from males and sperm were exposed to EE2 directly through the activation water. Direct exposure to EE2 had no effect on any measure of sperm swimming performance. In the second experiment, we exposed sexually mature male B. splendens to EE2 using a semi-static exposure protocol for 4 weeks. There were no significant treatment effects in the 10 ng L(-1) treatment group, but at the 100 ng L(-1) dose we found that fish had smaller gonads and reduced sperm swimming velocity. When allowed to interact freely with female conspecifics, males exposed to 100 ng L(-1) EE2 built smaller nests and showed a nonsignificant decrease in fertilization success. To investigate further the potential mechanism underlying the decrease in sperm quality, we repeated the chronic exposure experiment and analyzed the ATP content of sperm from fish in each treatment group. We found that males exposed to 100 ng L(-1) of EE2 had fewer moles of ATP per sperm than did fish in the other two treatment groups, suggesting that a decrease in intracellular ATP caused a reduction in sperm swimming velocity. The current study adds to the growing body of literature that indicates the risks to aquatic organisms of exposure to environmentally relevant concentrations of EE2.

Reproductive consequences of exposure to waterborne phytoestrogens in male fighting fish Betta splendens.

Phytoestrogens are plant compounds that can act as endocrine disruptors in vertebrates. Biologically active levels of phytoestrogens have been found in aquatic habitats near wood pulp and paper mills, biofuel manufacturing plants, sewage-treatment plants, and agricultural fields. Phytoestrogens are known to cause hormonal and gonadal changes in male fish, but few studies have connected these effects to outcomes relevant to reproductive success. In one experiment, we exposed sexually mature male fighting fish Betta splendens to environmentally relevant (1 µg L(-1)) and pharmacological concentrations (1000 µg L(-1)) of the phytoestrogen genistein as well as to a positive control of waterborne 17ß-estradiol (E2; 1 µg L(-1)), and a negative control of untreated water. In a second experiment, we exposed male B. splendens to environmentally relevant concentrations (1 µg L(-1)) of genistein and ß-sitosterol singly and in combination as well as to the positive and negative controls. All exposures were 21 days in duration. We measured sex-steroid hormone levels, gonadosomatic index (GSI), sperm concentration and motility, and fertilization success in these fish. We found that exposure to genistein did not affect circulating levels of the androgen 11-ketotestosterone or the estrogen E2 relative to negative-control fish. We also found that neither of the compounds nor their mixture affected GSI, sperm concentration or motility, or fertilization success in exposed fish relative to negative-control fish. However, fish exposed to phytoestrogens showed some evidence of fewer but more motile sperm than fish exposed to the positive control E2. We conclude that sexually mature male B. splendens are relatively immune to reproductive impairments from short-term exposure to waterborne phytoestrogens.

Regulation of high-affinity iron acquisition homologues in the tsetse fly symbiont Sodalis glossinidius.

Sodalis glossinidius is a facultative intracellular bacterium that is a secondary symbiont of the tsetse fly (Diptera: Glossinidae). Since studies with other facultative intracellular bacteria have shown that high-affinity iron acquisition genes are upregulated in vivo, we investigated the regulation of several Sodalis genes that encode putative iron acquisition systems. These genes, SG1538 (hemT) and SG1516 (sitA), are homologous to genes encoding periplasmic heme and iron/manganese transporters, respectively. hemT promoter- and sitA promoter-gfp fusions were constructed, and in both Escherichia coli and Sodalis backgrounds, expression levels of these fusions were higher when the bacteria were grown in iron-limiting media than when the bacteria were grown in iron-replete media. The Sodalis promoters were tested for iron regulation in an E. coli strain that lacks the fur gene, which encodes the iron-responsive transcriptional repressor Fur. Expression of the promoter-gfp fusions in the E. coli fur mutant was constitutively high in both iron-replete and iron-deplete media, and addition of either Shigella flexneri fur or Sodalis fur to a plasmid restored normal regulation. A Sodalis fur mutant was constructed by intron mutagenesis, and semiquantitative reverse transcription-PCR (RT-PCR) showed that iron repression of sitA expression was also abolished in this strain. In vivo expression analysis showed that hemT and sitA are expressed when Sodalis is within tsetse fly hosts, suggesting a biological role for these genes when Sodalis is within the tsetse fly.